Two of only seven of the machines in the world are being delivered to the UK, initially for use in clinical trials.

Each device is understood to cost more than a £3 million CyberKnife – a cutting-edge form of radiotherapy that hits hard-to-reach tumours with high-dose targeted beams.

One of them will be commissioned at the Royal Marsden Hospital’s site in Sutton, Surrey, early next year.

Professor Uwe Oelfke, from the Institute of Cancer Research and the Royal Marsden NHS Foundation Trust, said a major problem for radiotherapy was that patients’ internal anatomy changed “from day to day or even from second to second”.

Being able to view highly-detailed MRI images of a radiotherapy target site would allow far more accurate treatment with less damage to healthy tissue and fewer side effects.

“It’s extremely important for the success of radiation therapies that we can see what we want to treat at the time of the treatment, not diagnostic images which are basically reflecting the anatomical state a few days or weeks before the treatment,” said Prof Oelfke.